Comparison of methods for recovery of Clostridium difficile from an environmental surface

Abstract

Survival of Clostridium difficile in an aerobic environment is possible because of spore formation. When sodium taurocholate is substituted for the egg yolk of a selective medium, cycloserine-cefoxitin-fructose-agar (CCFA), enhanced recovery of C. difficile spores is shown. This selective medium (TCCFA) does not improve recovery of vegetative forms. In this study, dry and saline-moistened swabs, adhesive paddles, and Rodac plates containing CCFA and TCCFA were compared in their ability to recover C. difficile spores from an inoculated surface. Rodac plates grew 20 to 25 times as many spores on TCCFA as on CCFA. Saline-moistened swabs recovered fewer organisms than Rodac plates. Dry swabs and adhesive paddles rarely recovered spores. Prereduction of agar in an anaerobic chamber was not necessary for optimal spore recovery. Optimal growth of vegetative C. difficile required prereduced media. Agar prereduced for 2 h supported the growth of 12 C. difficile isolates as well as agar prereduced for 18 h. Vegetative cells of C. difficile survived for only 15 min in room air. Use of Rodac plates containing TCCFA is preferred for detection of C. difficile spores in the hospital environment.